Interlocking mechanism for electric switches



R. E. LARKIN Aug. 16, 1966 INTERLOCKING MECHANISM FOR ELECTRIC SWITCHES Filed Aug. 12, 1964 2 Sheets-Sheet 1 mntw 8AM im z'w z 4a Jaws 454mm Aug. 1966 R. E. LARKIN 3,267,223

INTERLOCKING MECHANISM FOR ELECTRIC SWITCHES Filed Aug. 12, 1964 2 Sheets-Sheet 2 3,267,223 INTERLOCKING MECHANISM FOR ELECTRIC SWITCHES Robert E. Larkin, Waukesha, Wis., assignor to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware ' Filed Aug. 12, 1964, Ser. No. 389,057

6 Claims. (Cl. 200-) This invention relates to interlocking mechanisms for electric switches and more particularly to switch interlocking mechanisms suit-able for portable electric tools having on-off switches together with reversing or two speed switches.

It is an object of this invention to provide an improved interlocking mechanism for a switch assembly including an on-off switch, together with another switch for selection of either motor speed or operating direction, whereby the switch controlling motor speed or direction cannot be operated while the on-olf switch is in the on position.

It is futher object of this invention to provide an interlocking mechanism of the aforedescribed type which is suitable for interlocking of minimally modified conventional switches of proven reliability. 1 It is still another object to provide a switch assembly of the aforedescribed type with an interlocking mechanism which occupies a minimum amount of space within the relatively confining interior spaces of portable tool housings and handles.

Various other objects and advantages of the invention will become apparent from the following description.

While the device hereinafter described is effective to fulfill the stated objects it is not intended that the invention be confined to the particular embodiment disclosed since it is susceptible of various modifications without departing from the scope of the appended claims.

In the drawings:

FIGURE 1 is a side view of an assembly incorporating the principles of the invention comprising two manually operable switches and an interlocking mechanism;

FIG. 2 is a top view of the switch assembly of FIG. 1;

FIG. 3 is a partially sectional view taken on line 33 of FIG. 2;

FIG. 4 is a fragmentary view in partial section taken on line 33 of FIG. 2, but with the switch illustrated in its opposite position;

FIG. 5 is an exploded isometric view of some of the elements of the interlocking mechanism;

FIG. 6 is a sectional view taken on line 6-6 of FIG. 3; and

FIG, 7 is a bottom view of the switch assembly illustrating an exemplary wiring arrangement for use with the switch assembly.

Referring to the drawings, the switch assembly includes a double-pole single-throw trigger operated tool handle switch 2 of a type described in detail in the George J. Meuer Patent No. 1,977,078 and a doublepole, double-throw slide operated switch 3 of a type more completely described in the Alvin W. Krieger Patent No. 2,011,293. A mounting plate 4a of slide switch 3 and a mounting bracket 4b of trigger switch 2 are welded together at the overlapped portion 4c to form a common mounting assembly 4.

Trigger switch 2 has a molded insulating base 5 for housing stationary and movable contacts (not shown) and associated press-in terminals 6, 7, 8 and 9 (FIG. 7) accessible via apertures in the lower surface of base 5. When in the on position the switch mechanism serves to electrically connect terminal 6 to terminal 8 and connect terminal 7 to terminal 9. An insulating plate 10 covers the top of base 5. A switch frame '11 having United States Patent 0 p ice the shape of an inverted channel rests atop plate 10. A thin sheet metal dust cover 12 is assembled over frame 11 with depending portions 12a and 12b for partially covering openings in frame 11 to reduce the entry of dust and other extraneous materials. A pair of rivets 13 pass through base 5, plate 10, frame 11, dust cover -12 and a pair of apertures in bracket 4b to fasten the assembly to mounting bracket 4b. A pair of upstanding lugs 14 extend from the edges of bracket 4b to pivotally support trigger 15 on a pin 16. A spring biased plunger 17 transversely slida'ble in the al-ined apertures of a pair of lugs 18 serves, when depressed against the spring bias, to lock the trigger 15 in its on position.

A pair of lugs 19 extend below bracket 4b to be pivotally connected by pin 20 to a pair of parallel arms 21a of a forked guide link 21 (FIG. 5). A guide pin 22 extends through and is fastened to a tab 21b at the other end of guide link 21. A pin 23 similar to pin 20 extends transversely through apertures in frame 11. A pair of tension springs 24 between the ends of pin 23 and pin 20 serve to pull pin 20 toward pin 23 and thereby bias the trigger I15 and the associated switch mechanism to the off position. The rounded lower end of guide pin 22 engages a generally hemispherical spring guide 25 at the upper end of an overcenter spring 26 of the conventional mechanism of switch 2. Pin 22 has a flanged upper portion 22a overlying the upper surface of tab 21b and having flattened parallel sides 22b. To operate switch 2, trigger 15 is depressed from the off position illustrated in FIGS. 1 and 3 to pivot about pin 16. Guide link 21 and guide pin 22 are there upon pulled to the right to move the upper end of spring 26 over center to cause completion of the circuits within switch 2. When pressure is removed from trigger 15, springs 24 reverse the movement, trigger 15 rotates clockwise and guide pin 22 moves toward the left. Spring 26 consequently moves overcenter and the mechanism returns to its 0 position.

Switch 3 is basically a conventional slide operated double-pole, double-throw switch. A base member 27 molded of a suitable insulating material has a substantially rectangular central main recess 27a. Four stationary contact members 28, 29, 30 and 31 are arranged within base 26 near the respective four corners thereof with contact portions extending into recess 27a and with terminal portions 28a, 29a, 30a and 31a extending from the lower surface of base 26. Two terminal and bearing plates 32 and 33 are supported in base 26 between stationary contacts 28, 29, 30 and 31 with terminal portions 32a and 33a extending from the lower surface of base 26. The upper ends of plates 32 and 33 are formed and recessed to provide bearings for the hooked ends of a U-shaped toggle contactor assembly comprising two generally S-shaped contactors 34 and 35 connected mechanically and insulated electrically at their lower ends by a molded insulating member 36 as best shown in FIG. 6. A rounded nib 36a on the upper surface of member 36 serves to retain the lower end of an overcenter compression spring 37. A spring guide 38 covers the upper end of spring 37.

A slotted insulating plate 39 covers the open top of base 26. A cylindrical spacer 40 and a rectangular spacer 41 are placed between plate 39 and mounting plate 4a. A pair of rivets 42 and 43 pass through base 26, plate 39, mounting plate 4a and the respective spacers 40 and 41 to fasten switch 3 to the assembly. A slide button operator 44 lies atop plate 4a and a depending pin 45 passes through plate 4a and the slot in insulating plate 39 to pivotally engage the spring guide 38. plate 46 is fastened to pin 45 below mounting plate to An insulating retainoperator 44 inslidable assembly with mounting plate 4a.

In a conventional manner, the reciprocation of button 44 between the position of FIG. 3' and the position of FIG. 4 serves to move the upper end of spring 37 over center. Consequently, contactors 34 and 35 are pivoted to electrically connect terminal 32a alternately to terminal 29a or terminal 28a and terminal 33a alternately to terminal 31a or 30a. By appropriate wiring, switch 3 can therefore be made to function as a two-speed or a revers- 7 ing switch.

Switches 2 and 3 are interlocked by means comprising a slider plate 47 and a spring member 48 with an attached pin 49. The substantially flat spring 48 comprises three portions 48a, 48b and 480 which are set at small angles to one another. Portion 48a is firmly anchored between spacer 41 and mounting plate 4a by rivet 43. The intermediate fiexible portion comprises two parallel elements 48b spaced apart to pass on either side of aperture 50 in plate 4a through which pin operates. Spring 48 is closed at its free end by portion 486. A recess 51 is formed therein for clearance of spacer 40. Pin 49 is securely fastened to portion 48c adjacent the end thereof to project upwardly into aperture 52 in plate 4a. Portions 48b and 48c are set at such angles to portion 48a that portion 48c angles downwardly away from portion 48b to form an inclined plane. The end of portion 48c and the attached pin 49 are thereby spring biased downwardly away from plate 4a.

The forked end of slider plate 48 is assembled below spring 48 so that the upwardly facing nibs 53 slidingly contact the lower inclined plane surface of portion 480. The forked arms 54 of slider plate 47 slidin-gly bear against the upper surface of insulating plate 39 and are spaced apart to clear spacer 40. A slot 55 is formed in slider plate 47 to clear one of the rivets 13. An aperture 56 in the end of plate 47 fits closely over the upper end 22a of pin 22 to thereby cause slider plate 47 to reciprocably move in unison with guide link 21 as trigger switch 2 is operated between its on and off positions.

When trigger 15 isdepressed to the on position guide link 21 and slider plate 47 move toward the right with reference-to FIGS. 3 and 4. As slider plate 47 moves to the right, nibs 53 slide to the right in contact with the lower inclined plane surface of portion 480. Since nibs 53 move in a horizontal direction and portion 480 angles downwardlyto the right, portion 480 and pin 49 are forced upwardly as trigger switch 2 moves to its on position. In FIG. 3, trigger switch 2 is shown in the off position. Pin 49 extends only slightly above the top surface of plate 48 and slide operator 44 is consequently free to move between its two operating positions without interference with pin 49. When trigger switch 2 is moved from its off position toward its on position, pin 49 is forced upwardly as previously explained to extend substantially above the upper surface of plate 4a as shown in FIG. 4. When pin 49 is in this extended position slide operator 44 is prevented from moving from one position to another. When slide operator 44 is in the leftward position as in FIG. 3, the extended pin 49 prevents rightward movement of operator 44 by interference with the right end surface of operator 44. When slide operator 44 is in its rightward position as shown in FIG. 4, pin 49, when raised, extends into a recess 57 in the lower surface of operator 44 to prevent leftward movement thereof. Upon release of trigger switch 2 to its off position, slide plate 47 returns to the left and the spring bias of spring 48 returns pin 49 to its retracted position of FIG. 3.

It can be seen therefore that the aforedescribed interlocking mechanism is eifective to prevent operation of slide switch 3 between its two operating positions when trigger switch 2 is moved from its off position. It can also be seen that slide switch 3 is free to move between its operation positions when trigger switch 2 is in its off position.

FIG. 7 illustrates exemplary connections which may be used to adapt switch 3 to function as a motor reversing switch while switch 2 serves as' an on-01f switch. Terminals 8 and 9 of switch 2 are connected to power lines L1 and L2, respectively. At the opposite sides of switch 2 terminal'7 is connected to a center terminal 33a of switch 3. Terminal 6 is connected to one side of the armature 58 of the motor which is typically of the universal type. The other side of armature 58 is connected to the other center terminal 32a of switch 3, Terminals 29a and 31a' are cross-connected to terminals 30a and 28a, respectively. Terminals 28a and 30a are connected to opposite sides of the motor field winding (not shown). Switch 2 is therefore effective to energize both the armature and field when moved to its on position, and operation of switch 3 a second switch having a base member and a movable operating member exterior thereto; mounting means to which said second switch is fastened, the operating member of said second switch.

being on one side of said mounting means and said base member being mounted in the opposite side of said mounting means; and interlocking means effective to prevent operation of said second switch when said first switch is moved fro-m its first position but to allow operation of said second switch when said first switch is in its first operating position c-omprisingi locking means mounted between said base member and said mounting means communicating to said one side of said mounting means via an aperture in said mounting means and having extended and retracted positions with respect to said one side of said mounting means;

reciprocatory meansmechanically linked to said first switch for movement between first and second positions as said first switch is operated between its corresponding first and second position;

and means engaging said locking means and operated by said reciprocatory means for moving, when said reciprocatory means moves to its second position, said locking means from its retracted position to its extended position to interfere with the movement of the operating member of said second switch by engagement therewith to thereby prevent operation of said second switch when said first switch is moved from its first position.

In an electrical switch assembly:

a first switch having first and second operating positions;

a second switch having a base member and an operating member exterior thereto operable between two operating positions;

mounting means to which said second switch is fas: tened, the operating member of said second switch being one side of said mounting means and said base member being mounted on the opposite side of said mounting means;

and interlocking means effective to prevent operation of said second switch when said first switch is in its second operating position but to allow operation of said second switch when said first switch is in its first operating position comprising:

a spring member mounted between said base member and said mounting means;

a locking member extending from said spring memher for movement through an aperture in said mounting means and having extended and retracted positions with respect to said one side of said mounting means;

a slide member mechanically linked to said first switch for movement between first and second positions as said first switch is operated between its corresponding first and second positions;

and means movable with said slide member engaging said spring member for moving, when said slide member moves to its second position, said locking member from its retracted position to its extended position to interfere with the movement of the operating member of saidsecond switch by engagement to thereby prevent operation of said second switch when said first switch is moved fro-m its first position. 7

3. In an electrical switch assembly:

a first switch having first and second operating positions;

a second switch having a base member and a sliding operator exterior thereto reciprocably operable between two operating positions;

a mounting plate to which said first and second switches are fastened, said sliding operator being on one side of said mounting plate and in close proximity thereto, and said base member being mounted on the opposite side of said mounting plate;

and interlocking means effective to prevent operation of said second switch when said first switch is'in its second operating position but to allow operation of said second switch when said first switch is in its first operating posit-ion comprising:

a substantially flat spring member mounted between said base member and said mounting plate, anchored securely at one end and having an inclined plane surface toward the free end thereof biased away from said mounting plate, locking means extending from said spring adjacent the free end thereof for movement through an aperture in said mounting plate and having extended and retracted positions with respect to said one side of said mounting plate;

a flat elongated slide member slidable between said spring and said base and mechanically linked to said first switch for movement between first and second positions as said first switch is operated between its corresponding first and second positions;

and means movable with said slide plate engaging the inclined plane surface of said spring member for moving When said slide plate moves to its second position, said locking means from its retracted position to its extended position to interfere with the movement of said sliding operator by engagement therewith to thereby prevent operation of said second switch when said first switch is moved from its first position.

4. The invention as defined in claim 3 in which said locking means comprises a pin fastened to and extending substantially perpendicular to said spring member.

5. The invention as defined in claim 3 in which said first switch is of the trigger operated type biased to said first operating position and is manually movable against its bias to said second operating position.

6. The invention as defined in claim 3 together with:

a contact making mechanism within the base member of said second switch;

a projection extending from the sliding operator of said second switch through an aperture in said mounting plate and mechanically connected to said contact making mechanism;

means fastening said spring member adjacent one end of said second switch, the free end of said spring member extending toward the opposite end of said second switch;

and an aperture located substantially centrally in said spring member, said projection passing freely therethrough for reciprocatory movement.

References Cited by the Applicant UNITED STATES PATENTS ROBERT K. SCHAEFER, Primary Examiner. 

1. IN AN ELECTRICAL SWITCH ASSEMBLY; A FIRST SWITCH HAVING FIRST AND SECOND OPERATING POSITIONS; A SECOND SWITCH HAVING A BASE MEMBER AND A MOVABLE OPERATING MEMBER EXTERIOR THERETO; MOUNTING MEANS TO WHICH SAID SECOND SWITCH IS FASTENED, THE OPERATING MEMBER OF SAID SECOND SWITCH BEING ONE SIDE OF SAID MOUNTING MEANS AND SAID BASE MEMBER BEING MOUNTED IN THE OPPOSITE SIDE OF SAID MOUNTING MEANS; AND INTERLOCKING MEANS EFFECTIVE TO PREVENT OPERATION OF SAID SECOND SWITCH WHEN SAID FIRST SWITCH IS MOVED FROM ITS POSITION BUT ALLOW OPERATION OF SAID SECOND SWITCH WHEN SAID FIRST SWITCH IS IN ITS FIRST OPERATING POSITION COMPRISING: LOCKING MEANS MOUNTED BETWEEN SAID BASE MEMBER AND SAID MOUNTING MEANS COMMUNICATING TO SAID ONE SIDE OF SAID MOUNTING MEANS VIA AN APERTURE 